Circuit Description
The PCM continuously monitors the Oxygen Sensor (O2S 1) activity for 100 seconds. During the monitor period, the PCM counts the number of times that the O2S 1 switches from rich to lean and from lean to rich and adds the amount of time that the O2S 1 took in order to complete all of the switches. With this information, you can determine an average time for all of the switches. If the average time to switch is too slow, a DTC P0133 will set.
Replace the entire oxygen sensor assembly if there is damage to the oxygen sensor pigtail wiring, the connector or the terminal. Do not attempt to repair the wiring, the connector or the terminals. The sensor must have a clean air reference provided in order for the sensor to function properly. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, the connectors or the terminals could result in the obstruction of the air reference and degrade the oxygen sensor performance. Refer to Heated Oxygen Sensor (O2S) Repair.
Conditions For Setting The DTC
| • | DTCs P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0506, P0507, P1406, P1441 not set. |
| • | The average O2S 1 response times are greater than 249mS for rich to lean sweeps or 249mS for lean to rich sweeps. |
Or
| • | Engine speed is between 1600 RPM and 2600 RPM. |
| • | Throttle Position (TP) angle is between 8% and 20%. |
| • | Ratio of response times is greater than 3.4 or less than 0.4 (manual trans.). |
| • | Evaporative emissions control system is commanded open for greater than 50% (manual trans.). |
| • | Purge learned memory is greater than approximately 191 (manual trans.). |
Or
| • | Ratio of response times is greater than 3.25 or less than 0.4 (auto trans.). |
| • | Evaporative emissions control system is commanded open for greater than 36% (auto trans.). |
| • | Purge learned memory is greater than approximately 128 (auto trans.). |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
| • | The coolant fan turns ON. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | The MIL/DTCs can be cleared by using the scan tool. |
Diagnostic Aids
DTC P0133 or slow response is most likely caused by one of the following items:
| • | Fuel pressure - The system will go rich if fuel pressure is to high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0133 may set. See Fuel System Diagnosis . |
| • | Leaking injector - A leaking or faulty injector can cause the system to go rich. |
| • | MAP sensor - An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected. |
| • | Pressure regulator - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator. |
| • | TP sensor - An intermittent TP sensor output can cause the system to go rich due to a false indication of the engine accelerating. |
| • | O2S 1 contamination - Inspect O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The sensor may have a white powdery coating and result in a high but false voltage signal (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.
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If no faults have been found at this point and no additional DTC's were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||||||||||||
2 | Were any component DTC's set? | -- | Go to Component DTC tables | |||||||||||
3 |
Do the parameters show averages less than the specified values or ratios less than or greater than the specified values? | 249 ms 249 ms 0.4 3.4 | ||||||||||||
4 | Visually/physical inspect the following items:
Was a problem found in any of the above areas? | -- | ||||||||||||
5 | Check the exhaust manifold for an exhaust leak near the engine. Repair as necessary. Was a exhaust leak found? | -- | ||||||||||||
6 |
Does the scan tool voltage indicate voltage within specified values? | 407-509 mV | ||||||||||||
7 |
Does the scan tool voltage indicate the voltage below the specified value? | 200 mV | ||||||||||||
8 |
Notice: Determine and correct the cause of the contamination in order to prevent damage to the replacement sensors.
Replace the Oxygen Sensor (O2S 1). Is the action complete? | -- | -- | |||||||||||
9 | Repair the condition as necessary. Is the action complete? | -- | -- | |||||||||||
10 | Repair the O2S 1 sensor signal circuit for a short to ground. Is the action complete? | -- | -- | |||||||||||
11 |
Does the O2S 1 voltage measure above the specified value? | 407 mV | ||||||||||||
12 |
Was an O2S 1 low circuit problem found and corrected? | 5 ohms | ||||||||||||
13 |
Was an O2S 1 sensor signal circuit problem found and corrected? | 5 ohms | ||||||||||||
14 | Check the O2S 1 sensor low circuit terminal connection at the PCM and then replace the terminal if necessary. Did the terminal require replacement? | -- | ||||||||||||
15 | Check the O2S 1 sensor signal circuit terminal connection at the PCM and replace the terminal if necessary. Did the terminal require replacement? | -- | ||||||||||||
Replace the PCM. Is the action complete? | -- | -- | ||||||||||||
17 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||||||||||||
Check if any additional DTC's are set. Are any DTC's displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK, Refer to Diagnostic Aids |
